This invention relates to devices for advancing an end portion of a supply length of heat sealable film along a path to an applying station, sealing the end portion across the lip of a cup, and severing the applied end portion from the strip of film.
U.S. Pat. Nos. 3,286,437, 3,501,896 and 4,050,971 show such devices. The devices described in U.S. Pat. Nos. 3,286,437 and 4,050,971 however, make no provision for a straw hole in the applied film, so that to insert a straw in a cup sealed by those devices a user must either peel a portion of the film away from the lip of the cup or puncture the film with an implement, either of which procedures are inconvenient and can result in spilling some of the contents of the cup.
Attempts have been made to form an opening (as suggested in U.S. Pat. No. 3,501,896) or perforations in the film at the time it is applied at the applying station by use of a punch mounted at the applying station. The results of such attempts have not been satisfactory, however. The punch becomes heated and collects material from the film and from the food or drink within the cups. This collected material provides a potential source of contamination for the food or drink in cups being sealed, and greatly reduces the cutting efficiency of the punch so that it will not reliably perform its cutting function.